1. Field of the Invention
The present invention relates to an air bag in use for a head protection air bag device. More particularly, the invention relates to an air bag which, while being folded, is stored in the upper fringe of the openings on the cabin-inside side, and develops and inflates to cover the openings when receiving the inflation gas, and includes front- and rear-seat inflation chambers located at positions near the sides of front and rear seats.
The present application is based on Japanese Patent Application No. 2000-232201, which is incorporated herein by reference.
2. Description of the Related Art
A conventional head protection air bag device is constructed with an air bag and an inflator of the cylinder type for supplying inflation gas to the air bag (DE 29806200 Ul and GB 2324068, and the like).
The air bag, while being folded, is stored in the upper fringe of the openings on the cabin-inside side, and develops and inflates to cover the openings when receiving the inflation gas, and includes front- and rear-seat inflation chambers respectively located at positions near the sides of front and rear seats.
The air bag includes a gas inflow part which is located at the rear upper part and coupled to an inflator so as to flow inflation gas from the rear side into the air bag per se, and a main body including a front-seat inflation chamber and a rear-seat inflation chamber, and develops and inflates to cover the openings when receiving the inflation gas.
In addition to the front- and rear-seat inflation chambers, the air bag further includes a gas passage extending forwardly from the gas inflow part and being disposed above the front- and rear-seat inflation chambers and allowing the inflation gas to flow from inflow ports opened in the upper parts of the front- and rear-seat inflation chambers to the front- and rear-seat inflation chambers per se.
In the conventional head protection air bag device, the gas passage is extended forwardly from the gas inflow part linearly and substantially horizontally.
With this, the gas passage is filled, to a certain extent, with inflation gas over its entire length, and then the inflation gas flows into the front- and rear-seat inflation chambers via inflow ports associated therewith. There is room for improvement in quickly start the developing and inflating of the folded front- and rear-seat inflation chambers below.
In particular above the rear-seat inflation chamber, the inflation gas flowing forward through the gas passage is strong. Accordingly, in the initial stage of the passage of the inflation gas, inflation gas sometimes is hard to flow into the rear-side peripheral edge. Accordingly, there is room for improvement in securing a quick start of the downward developing/inflating operation.
A possible measure taken for this is to change the gas flowing passage so as to end the developing/inflating operation of the rear-seat inflation chamber and to develop and inflate the front-seat inflation chamber. This measure, however, further delays the ending of the developing/inflating operation of the front-seat inflation chamber which is likely to delay its developing/inflating operation, because the front-seat inflation chamber is remote from the gas inflow part.
Accordingly, an object of the present invention is to provide an air bag in use for a head protection air bag device which lessens a delay of the ending of a developing/inflating operation of a front-seat inflation chamber, and quickly starts a developing/inflating operation of a rear-seat inflation chamber.
To achieve the above object, there is provided an air bag in use for a head protection air bag device in which the air bag, while being folded, is stored in the upper fringe of the openings on the cabin-inside side, and includes a gas inflow part, located at the rear upper part, for flowing inflation gas into the air bag and a main body which develops and inflates to cover the openings when receiving the inflation gas, the main body including front- and rear-seat inflation chambers, located at positions near the sides of front and rear seats, for receiving inflation gas, and a gas passage extending forwardly from the gas inflow part and being disposed above the front- and rear-seat inflation chambers and allowing the inflation gas to flow from inflow ports opened in the upper parts of the front- and rear-seat inflation chambers to the front- and rear-seat inflation chambers per Se. The air bag is improved such that the inflow port of the rear-seat inflation chamber is opened in a direction substantially orthogonal to an axial direction of the gas passage, and a front-side peripheral edge is disposed to be higher than a rear-side peripheral edge.
The air bag thus constructed may have such a preferable construction that a plurality of inflow ports of the front-seat inflation chamber are opened in a direction substantially orthogonal to an axial direction of the gas passage, while being arrayed along the gas passage, and a guide is formed on the peripheral wall of the gas passage located above the plurality of inflow ports for the front-seat inflation chamber, and directs downwardly part of the inflation gas flowing forwardly and guides the inflation gas from the inflow port of the rear-seat inflation chamber into the front-seat inflation chamber.
In the air bag thus constructed, inflation gas flows from the gas inflow part into the main body. Then, the inflation gas passes through the gas passage extending forwardly and flows forwardly. As recalled, the inflow port of the rear-seat inflation chamber is opened in a direction substantially orthogonal to an axial direction of the gas passage, and a front-side peripheral edge is disposed to be higher than a rear-side peripheral edge. Accordingly, the front-side peripheral edge of the inflow port is easy to interfere with the inflation gas by an extent corresponding to the dimension by which the front-side peripheral edge is higher than the rear-side peripheral edge. The front-side peripheral edge directs the inflation gas resulting from the interference to the rear-seat inflation chamber. This leads to a quick start of the developing/inflating operation of the rear-seat inflation chamber.
The inflow port of the rear-seat inflation chamber has merely such a configuration that it is opened in the direction substantially orthogonal to the axial direction of the gas passage, and its front-side peripheral edge is higher than its rear-side peripheral edge. Such a configuration of the inflow port cannot direct the entire inflation gas flowing forwardly within the gas passage to the rear-seat inflation chamber, as a matter of course. Therefore, a delay of the ending of the developing/inflating operation of the front-seat inflation chamber may be minimized by appropriately adjusting a height of the front-side peripheral edge from the rear-side peripheral edge.
Accordingly, the air bag of the embodiment which is used for the head protection air bag device is capable of minimizing the delay of the ending of the developing/inflating operation of the front-seat inflation chamber, and quickly starts the developing/inflating operation of the rear-seat inflation chamber.
Where the air bag has the preferable construction as stated above, the developing/inflating operation of the front-seat inflation chamber is also quickly started.
The inflation gas flows forwardly through the rear passage above the front-seat inflation chamber and flows to the upper part of the front-seat inflation chamber. As recalled, the guide is formed on the peripheral wall of the gas passage located above the plurality of inflow ports for the front-seat inflation chamber. Therefore, part of the inflation gas flowing forwardly is directed downwardly by the guide, and guided into the front-seat inflation chamber, from the inflow port on the rear side. As a result, the developing/inflating operation of the front-seat inflation chamber is quickly started.
Also in this case, the inflation gas may smoothly be introduced from the inflow ports into the front-seat inflation chamber on the front side of the inflow port by appropriately adjusting the downward projection quantity of the guide, as a matter of course. As a result, the front-seat inflation chamber being folded is developed downward from the substantially entire region as viewed in the front/rear direction. This leads to quicken the ending of the developing/inflating operation of the front-seat inflation chamber.
Features and advantages of the invention will be evident from the following detailed description of the preferred embodiments described in conjunction with the attached drawings.